jor2daje wrote:the only issue I see is getting a good seal between syringe and your homemade fill valve, perhaps stick with a schrader with spring removed and just epoxy a good valve cap onto your syringe.
It's actually in my interest to eliminate the schrader, it will help with the arcing problems I was having for small diameter cartridges. As to getting a good seal, the push-fit between the syringe nozzle and the cut down needle will be very good.
Ever tried that old trick of sticking a syringe needle (we're talking the ones with a removable needle like
these) in soap or wax in order to block it, then pushing the plunger until the needle segment pops off? Many times, the needle won't come off even if you take the plunger to the end because it's such a tight fit. So not worried there
The other thing would be to do the initial fill without a projectile in so the unmixed air can simply flow on the barrel, if you dont do this you are adding to atmospheric air already in the chamber which could mess with your mix, especially in such small volumes.
As SpudFarm pointed out, this can easily be compensated for by adding the cartridge volume to the syringe volume when calculating the amount of fuel to be added.
I haven't followed your cartrige project to much as I thought you where going to make some complex setup that was impossible to make reasonably cheaply.
With cartridges, it's either cheap and simple or not worth doing, hence the focus on developing the right design instead of just saying "feck it" and making the effort to produce a complex design.
I'll keep thinking about any potential improvements throughout the day, if I can't think of any improvements the prototype will probably look something like the diagram above.
If this works, the hybrid pengun might actually be feasible
